The present invention relates to non-contact methods for measuring quantity of sebum or oil on skin or other substrates. While measurement can be done in vivo or ex vivo, the technique is preferred for use in vivo because of the ability to measure formation of oil on the skin in real time.
Methods of analyzing the quantity of sebum or oil produced using so-called contact techniques are known. Generally such contact methods mean that the measurement involves contact with the area where the sebum/oil is being measured. Since the sebum or oil is generally sampled and then measured, it is difficult or impossible to monitor changes in real time, i.e., as they are occurring. For example, xe2x80x9cIn-vivo infrared analysis of the recovery of sebaceous lipids after dilapidationxe2x80x9d, J. Invest. Dermatology, 112(4), 779 (1999), N. Kollias et al. describe an ATR-FTIR method for sebum detection using a fiber optic probe attachment. This is a contact method involving collection and transfer of sebum onto an ATR (attenuated total internal reflection device) crystal. Other contact methods include use of sebutape, use of a sebumeter and lipid extraction.
JP 09292214 (assigned to Sekisui Chemical) discloses a non-contact ultrasound method for measuring skin sebum. Here however, the ultrasound measures only the thickness of the fat layer, not actual amounts of sebum produced.
Other non-contact methods are also disclosed in the following references.
In JP 05060686, sebum is collected from the surface using a plate and then an IR spectrum is obtained using ATR device.
In JP 02220630, sebum quantity is measured using IR lights to detect reflected light from sebum collecting surface.
In U.S. Pat. No. 5,094,248 to Kawam, sebum is collected onto a hydrophilic open celled microporous polymeric film by patching to skin, and the amount of sebum collected is measured against a selected background by optical methods.
In U.S. Pat. No. 4,224,950 to Bore et al., sebum is collected onto a frosted glass plate and quantified using optional methods.
In U.S. Pat. No. 4,313,393 to Barbuscio et al., sebum is collected using an oil absorbent material, and the amount collected is quantified using a dye.
In WO 96/25884 to (assigned to Courage and Khazaka), sebum secretion on skin is measured using a microporous water repellent, sebum absorbing opaque foil which absorbs sebum and changes in transparency.
None of these methods are true xe2x80x9cnon-contactxe2x80x9d methods and, therefore, they do-not allow monitoring sebum levels in vivo in real time.
Unexpectedly, applicants have discovered that it is possible to measure quantity of sebum or oil in vivo using non-contact technique. This also allows real time measurement.
The present invention relates to a non-contact (non-invasive) method for measuring quantity of sebum or oil on skin substrate. Because the measurements are truly non-contact, they can be made in real time on the same sites for any desired length of time.
The present invention discloses one specific embodiment for non-contact measurement. A second embodiment is disclosed in a separate application filed on same day as the subject application.
In the present invention, the amount of sebum or oil is detected by diffuse reflectance, in the near-IR to mid-IR range (400 cmxe2x88x921 to 10,000 cmxe2x88x921). The measurement is made by choosing a desired spot (typically 0.1 to 10 cm) on the subject""s body (e.g., forehead); positioning a fiber optic probe on the spot about 0.1 to 40 cm away from the spot reflecting infrared (IR) light (typically of wavenumber 400 to 10,000 cmxe2x88x921) against the spot; and measuring the IR reflectance spectra in the wavenumber range. Analysis and quantification is achieved via chemometrics as described in the examples (i.e., using C-H and triglyceride overtone absorbance near defined wavenumber).. In an alternative embodiment, the method can be used for near infrared (NIR) imaging to measure oil/sebum on the desired substrate in specified wavenumber range.
More specifically, the invention comprises a non-contact process or method for measuring sebum or oil from skin or other substrate comprising:
(1) choosing a desired spot, typically 0.1-10 cm, preferably 0.2-9 cm, more preferably 0.2-3 cm on the body of a subject;
(2) positioning a fiber optic probe on the spot about 0.1-40 cm, preferably 0.1 to 2 cm away from the spot;
(3) reflecting infrared light in the 400 to 10,000 cmxe2x88x921 wavenumber range against said spot; and
(4) measuring an infrared reflectance spectra in said wavenumber range (e.g., using info gathered from the absorbance of C-H overtone combination bands in the 5000-7000 cm-1 range).
As noted, step 4 measurement may alternatively comprise near IR imaging to measure oil/sebum in specified wavenumber range.